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This work presents and validates experimentally new methodologies to design Maximum Power Point Tracking (MPPT) control strategies for variable speed wind turbines. The first technique of this study is an Extremum Seeking (ES) control strategy with no requirements for wind turbine model or wind speed measurements. As a comparison, Perturb and Observe (P&O) and Power Signal Feedback (PSF) are also designed and tested. All of the approaches are verified in Matlab simulations and experimentally tested with a lab-scale wind turbine and a fully instrumented wind tunnel. As a result, this work presents a new ES control algorithm that takes into account the energy production and rotor life expectancy.Furthermore, this work also considers wind farm level optimal control. The power generation of a wind farm depends on the efficiency of the individual wind turbines in the farm. In large wind farms, wind turbines affect aerodynamically each other. Previous studies suggest that a way to maximize the power generation of the wind farm is to reduce the generation of the wind turbines of the first rows to allow the next rows to generate more power (Case 2). Yet, other studies indicate that the maximum generation of the wind farm is reached when every wind turbine works at its optimum power coefficient Cp (Case 1). This work studies this controversy and proposes a method to evaluate when the wind farm should be coordinated as Case 1 or as Case 2. The discussion is based on the mathematical model of the wind farm, numerical computations and wind tunnel experiments.

The focus of this thesis is to improve the economic viability of wind energy and help integrate wind into the electric system. Wind energy plays a key role in meeting the renewable energy demands in the United States. Currently, wind farms experience a significant loss of power production due to the interactions between wind turbines when their individual performance is maximized. The main technical goal of this research is to develop techniques to obtain simplified models that will be used to properly coordinate wind turbines for more efficient operation of wind farms.